Field of the Invention
This invention relates to low voltage power distribution systems for any purpose, such that it may be classified as "track", which is generally used at high or mains voltage. This invention incorporates within its scope of usefulness the ability to function with a variety of lampholders such as are incorporated in this invention, or existing art lampholders that may be adapted to fit. Therefore the invention may be considered in whole, or any of the identified parts to be a track lighting system, but is not necessarily limited to being used for lighting purposes. As considered a track lighting system its primary function is for display and accent lighting, but it is not limited to these uses.
Background and Description of Prior Art
Historically, flexible lighting systems such as track were limited to high or mains voltage, such as 120 volt, that utilized 120 volt lamps. In the past decade there has been a vast increase in lamp technology that utilizes low volt design, low voltage being under 30 volts. As the lighting industry has attempted to to adapt to the increasing demand for low voltage lamps manufactures have created lamp holders that would reduce the voltage at each individual lamp, rather than attempt to create a completely new design. There are many challenges in using the previous approach, the high volt distribution system is adequate but the lampholders are generally prone to regular component failures due to the extreme heat build up with the lamp and transformer being in the same housing. There also tends to be quite a bit a noise, generally humming, that is created by the use of the small transformers used in the high volt systems.
To address these problems it seemed necessary to design a system that would allow the use of much larger and more reliable transformers that would be placed in remote locations, such as a cabinet, closet, or ceiling. Remotely locating the transformers moves the heat and noise generated by the transformer(s) to a location that is not a nuisance. Existing art for low voltage distribution: U.S. Pat. Nos. 4,776,809, S Hall; 4,837,667, T Grau. The design by Hall is based on using an expensive to produce series of extrusions and lacks flexibility in installation. The design by Grau is based on an exposed pair of conductors that are structurally and requires that it be tensioned between two surfaces. Neither of these systems are capable of being mounted suspended from the ceiling, nor is either system capable of being wired for more than one control circuit.
Upon setting out to accomplish this task it became obvious that there were many considerations that must be met:
The major difficulty in low voltage power distribution is overcoming the tendency of power drop (voltage drop) in the distribution system while maintaining a high wattage, or current, capacity. This is overcome by using multiple conductors to increase the conductor area for wattage capacity and/or to provide multiple circuit control.
The next challenge was to design a series of components that would be modular for maximum design flexibility at a minimum tooling and production cost. This was accomplished by using standard (previous art) components, whenever possible, that are used as made, or are modified to accomplish the task.
The next challenge was to design an electrical splice joint that is capable of handling the high currents inherent to low voltage, without oxidation, and within the space constraints of the visual qualities of the design. It was also necessary to design the splice joint so that it could be made by an experienced electrician without special tools, and would also support the structure of the housing across the splice. The difficulties of the joint were overcome by using a retractable sleeve that would not interfere with the splicing of the conductors, the splices could be made using existing art electrical connectors such as crimp style or set screw style (typically called euro style) connectors. Once the electrical splice was accomplished the sleeve would be moved over the area of the joint and locked onto both tube sections providing a suitable mechanical connection of the housings.
The final challenge in the power distribution was having access to the current in the conductors running through the housing of the system. This was accomplished by using a tap or splice that may be mechanical or soldered to supply female receptacles that would be located in the wall of the fixture housing at predetermined locations. The receptacles would be wired into alternate sets of wires so that every other receptacle would be fed from a different, or alternate circuit, such as when the system is wired with two or more transformers. This is useful in many applications, particularly when different light levels are desired by way of dimming.
Once the challenge of distributing the power over a large area was accomplished it was then necessary to design a series of appropriate lampholders that would be attachable to the power distribution system's housing, in this case the tubing. These fixtures generally utilize existing art clamps and coiled electrical cords that attach to the tubing to provide a basis from which a lampholder may be attached. Coil cords were chosen for flexibility in length and their ability to self maintain, so as not to create the hazard of stray wires.
The biggest challenge was to design versatile lampholders that would require the least number of components and would also allow the most flexibility to the end user. The other major consideration was the heat given off by the lamps that would be used, typically tungsten halogen, which create high temperatures in a small space. Previous art: see U.S. Pat. Nos. 4,760,509 and 4,703,404 both by Helton & Panagiotou. In these lampholders the fixtures are quite elaborate and require many difficult to fabricate parts, which increases design, tooling and production costs. These lampholders are also limited in their ability to accept accessories that are required to effectively control the beam emitted from the lamps.
As a result the lampholders were designed to utilize a "U" shape yoke frame that would spread open and spring back to allow the insertion and removal of the components, typically rings. These rings would be the basis of the lampholder's function. The rings would retain the safety glass explosion shield and the lamp.
The lampholders were designed to accept a wide range of accessories such as colored filters and louvers. They were also designed to retain a glass cover that would provide a safety shield in the event of the explosion of one of the lamps.
Another challenge was to be able to overcome the heat build up that typically causes failure of lampholder components. This was accomplished by making the rings open whenever possible, as long as it did not leave the electrical contacts exposed. In one instance the open rings are reversible to provide a snooted or open front. Using the least amount of material and having as many openings as possible increases the cooling capacity of the lampholder.